Some remarks on the paper 'Symmetries and generalized W-infinity algeb
ra of the modified KP equation' (S. Y. Lou and G. J. Ni, Lett. Math. P
hys. 34 (1995), 327-331) are given. It is pointed out that if we consi
der the inverse operator of a differential operator to be a linear ope
rator, the vector fields sigma(n)(v)(f) defined in the above Letter ar
e not certain to be symmetries of the modified KP equation under consi
deration.